Combined multistage power plant having a rotary compressor serving as the low pressure stage and a rotary pressure-wave machine serving as the high pressure stage



Aug. 27. 1968 E4 JENNY 3,398,525

COMBINE!) MULTISTAGE POWER PLANT HAVING A ROTARY COMPRESSOR SERVING AS THE LOW PRESSURE STAGl-l AND A ROTARY PRESSURE-WAVE MACHINE SERVING AS THE HIGH PRESSURE STAGE Filed July 21, 1965 PRESSURE-WAVE ACHINE EXHAUST- GAS [BOILER ,P 8

ADJUSTABLE 1 6 BLADING m TURBINE F 1 ATOMIC REACTOR V COQLERS 1 MHD 6 1 1o GENERATOR F L 3 3 F 2 INVENTOR. E I'I'IS {1 JE n Fig BY [3 1'. 3 1

United States Patent ABSTRACT OFTHE DISCLOSURE A combined multistage power plant includes a conventional rotary compressor serving as the low pressure stage and a pressure-wave machine servingas the high pressure stage. Compressed gas at the discharge side of the compressor is led through the compression stage of the pressure-wave machine. After heating, all of the compressed and hot working gas is then partially expanded such as in a gas turbine to give off some power and is then led through the expansion stage of the pressure wavemachine, all of the gas then being passed into an engine 'such as, for example, a second gas turbine operating on the same shaft as the compressor and first turbine. In lieu of the turbine, an MHD generator can be utilized to receive the gas from the pressure-wave machine. The heating means for the gas can be either a conventional combustion chamber or an atomic reactor.

This invention relates to an improved combined power plant with a conventional compressor as the low-pressure stage and an aerodynamic pressure-wave machine as the high-pressure, or high-temperature stage, the working gas flowing sequentially through at least the compressor, the compression stage of the pressure-wave machine and, after heating, through the expansion stage of the pressurewave machine and an engine.

In thermal actions, an attempt is made to locate the working range of the engine in as high a temperature range as possible. However, there are technological limits to arbitrary increases in temperature. It has, therefore, been proposed to place an aerodynamic pressure-wave machine before the engine. Such machines are suitable for higher inlet temperatures than a gas turbine, for example, because they are relatively simple in construction and are intrinsically well cooled. In addition, when a gas of low molecular weight, for example helium, is used, it is capable of processing a gradient which would require a large number of stages in the case of a conventional turbo-machine.

However, there is a hindrance in the way of general use of the pressure-wave machine. As an energy-balance shows, more power is delivered in the expansion which takes place at high temperature than has to be expended on the cold side for compression. In order to restore the balance, either some of the compressed air may be taken off for other purposes, as is known from one plant, or only part of the hot combustion gases may be passed through the pressure-wave machine, and the remainder cooled by the admixture of cold gases to the temperature which is permissible before an engine, or a drop in pressure must be forcibly created by throttling, for example in the combustion chamber. All the said possibilities lead to a reduction in the efliciency of the whole power plant.

The present invention is based on the problem of developing an arrangement for operating a combined power plant with an aerodynamic pressure-wave machine, in

3,398,525 Patented Aug. 27, 1968 Ice which the pressure-wave machine works at good efiiciency, with the result that the overall efiiciency of the plant is improved. According to the invention, this is achieved as a result of the fact that all of the compressed and heated working gas partially expands and gives off power before entering the expansion stage of the pressure-wave machine. One possibility of carrying out this mode of operation is offered by a gas turbine through which all of the working gas flows before entering the expansion stage of the pressure-wave machine.

In principle, the gas turbine may be interposed at any point in the flow path of the working gas between the compression and expansion stages of the pressure-wave machine. If the permissible temperature before the gas turbine is equal to the maximum attainable action temperature, it is placed immediately before the inlet of the pressure-Wave machine, and may indeed be combined with it to form a structural unit. This can be done for example if it 'is possible to cool the turbine with tolerable expenditure. However, such a possibility is lacking in the present state of development, and so the gas turbine must be interposed in the circulatory system before the working gas has been heated to the maximum action temperature. Three examples of embodiment which indicate re-heating of the working gas after the gas turbine are accordingly also diagrammatically illustrated in the accompanying drawing. In all the figures, the same components bear the same reference numbers.

FIGURE 1 shows a plant with open action, i.e. with internal combustion. The combustion air is compressed in the compressor 1 and in the compression stage of the aerodynamic pressure-wave machine 2, and raised in the combustion chamber 3 to a temperature which is still just permissible for the gas turbine 4 in which the Working gas partially expands and gives off power. In the combustion chamber 5, the working gas reaches the maximum temperature of the action, and then passes through the expansion stage of the pressure-wave machine 2 and an engine, in the present case a gas turbine 6. If the temperature after the pressure-wave machine is still too high for entry to the turbine 6, a boiler 7 may be interposed. Likewise, the working gas emerging from the turbine 6 can act on an exhaust-gas boiler 8 before emerging to atmosphere. The steam generated serves to drive a steam turbine 9 which drives an electrical generator 10.

The pressure-ratio in the gas turbine 4 is so chosen, and is necessarily so capable of regulation by adjustable blades, that at all load points the expansion stage of the pressure-wave machine delivers at the highest possible efliciency the power required in the compression stage.

FIGURE 2 illustrates a power-plant with closed circulation for the working gas and an atomic reactor as the heatsource. Helium, for example, is compressed in the compressor 1, re-cooled in the cooler 11, and raised to maximum action pressure in the pressure-wave machine 2. In the two heat-exchangers 12 and 13 connected in series on the high-pressure side, the gas reaches the permissible inlet temperature for the gas turbine 4. After the turbine, the gas flows through the atomic reactor 14, where it is heated to maximum action temperature, whereupon it flows through the expansion stage of the pressure-wave machine 2, the heat-exchanger 13, the gas turbine 6 and the heat-exchanger 12. After the cooler 15, the gas passes again to the starting point before the compressor 1, thus completing the circulation. In this example, also, exhaustgas boilers may be interposed for steam-generating purposes.

A similar plant is illustrated in FIGURE 3, but a magnetohydrodynamic generator 16 is used as the engine. Since the temperature at the inlet to this generator must be as high as possible because of the necessary electrical conductivity of the working gas, the latter, after emerging f om the p n n stag the pre u r ave achin 2, is passed via the pipe 17 through the reactor 14 again,

and heated to maximum temperature before being fed to thegenerator 16. s i

.r An auxiliary drive 18' might be necessaryjor starting and part-load running, and an electric motor, or turbine maybe provided fqr this purpose. Startingrnay also be carried out by suddenly discharging into thepipe system before the expansionstage of the pressure-wave machine a stored volume of gas'at increasedpressure. Thepressurewave machine must first of allj'be brought up to the correct speed.

, In all' figures of the drawing, thepressii're waveifiachine may be embodied with rotatingor stationary cells,

the engine and working machines may be arranged on a common shaft or combined to formsuitable groups, heat-exchangers may be provided instead of thefboilers for heating the combustion air, and likewise it is possible for the compressed working gas to undergo intermediate cooling in the compressor. Such or similar variants are included in the invention, but have not beenincorporated ,in'the drawing since they do not serve directly forcarrying out the idea of the invention.

I claim:

1. In a combined multistage power plant, the combination comprising a rotary compressor serving as the low pressure stage, a rotary' aerodynamic pressure-wave machine serving as the high pressure stage, duct means conveying all of the working gas sequentially through at least said compressor, the compression stage of said pressure-wave machine and thence through the expansion stage of said pressure-wave machine and an engine, means in the'jpre ssurej ratio of said gas turbm'e is adjustable 4 i eat a ptgthesw hia j asup ie e te n h egrpansion stage of said pressure-wave machine, and a gas turbine through which 'alllof said heated working gas flows after leaving the compression stage of said pressureaye machine and prior to entering said expansion 3. Aicomb'ined power plant as defined in claim'l 'where- 'Whereby an approximationto the "optim'urnoperating con- 4 iti'ons at "said pressure-wave machine can be attained at .v I h l "4. A combined powerplahtas defined in claim 1' and which includes means for ire-heating said working gas after passing through saidexpansion stage of said pressure-wave machineand prior to ehteringsaid engine.

References Cited UNITED srATEsPA 'E Ts 4/1947 Smith 60-3947 2,418,911 2,428,136- 9/1947 Barr 6039.17 2,738,123 3/ 1956, Hussmann 6039.45 XR 3,218,807 11/19652 Berchtold et a1. 60-3945 XR JULrUs wasmrimay Examiner, I 

